Inline some afm parsing code.

anntzer · anntzer · commit e1d2ae375eb3 · 2019-08-25T00:11:59.000+02:00
Splitting _parse_afm out of `__init__` doesn't buy much, and its
docstring is not particularly informative either, so just inline
it to the AFM constructor.  Likewise, most of the benefits from
`_sanity_check` can be obtained by just looking for the first entry of
the header (this admittedly relies on dict-order-maintaining, which is
present on Py3.6 though not mandated (it is mandated in Py3.7), but I'm
not aware of Matplotlib running on an alternative Py3.6 that does not
support that behavior...).
diff --git a/lib/matplotlib/afm.py b/lib/matplotlib/afm.py
@@ -85,25 +85,6 @@ def _to_bool(s):
         return True
 
 
-def _sanity_check(fh):
-    """
-    Check if the file looks like AFM; if it doesn't, raise `RuntimeError`.
-    """
-    # Remember the file position in case the caller wants to
-    # do something else with the file.
-    pos = fh.tell()
-    try:
-        line = next(fh)
-    finally:
-        fh.seek(pos, 0)
-    # AFM spec, Section 4: The StartFontMetrics keyword [followed by a
-    # version number] must be the first line in the file, and the
-    # EndFontMetrics keyword must be the last non-empty line in the
-    # file. We just check the first line.
-    if not line.startswith(b'StartFontMetrics'):
-        raise RuntimeError('Not an AFM file')
-
-
 def _parse_header(fh):
     """
     Reads the font metrics header (up to the char metrics) and returns
@@ -157,13 +138,11 @@ def _parse_header(fh):
         if line.startswith(b'Comment'):
             continue
         lst = line.split(b' ', 1)
-
         key = lst[0]
         if len(lst) == 2:
             val = lst[1]
         else:
             val = b''
-
         try:
             converter = header_converters[key]
         except KeyError:
@@ -175,8 +154,16 @@ def _parse_header(fh):
             _log.error('Value error parsing header in AFM: %s, %s', key, val)
             continue
         if key == b'StartCharMetrics':
-            return d
-    raise RuntimeError('Bad parse')
+            break
+    else:
+        raise RuntimeError('Bad parse')
+    # AFM spec, Section 4: The StartFontMetrics keyword [followed by a version
+    # number] must be the first line in the file, and the EndFontMetrics
+    # keyword must be the last non-empty line in the file.  We just check the
+    # first header entry.
+    if next(iter(d)) != b'StartFontMetrics':
+        raise RuntimeError('Not an AFM file')
+    return d
 
 
 CharMetrics = namedtuple('CharMetrics', 'width, name, bbox')
@@ -366,40 +353,13 @@ def _parse_optional(fh):
     return d[b'StartKernData'], d[b'StartComposites']
 
 
-def _parse_afm(fh):
-    """
-    Parse the Adobe Font Metrics file in file handle *fh*.
-
-    Returns
-    -------
-    header : dict
-        A header dict. See :func:`_parse_header`.
-    cmetrics_by_ascii : dict
-        From :func:`_parse_char_metrics`.
-    cmetrics_by_name : dict
-        From :func:`_parse_char_metrics`.
-    kernpairs : dict
-        From :func:`_parse_kern_pairs`.
-    composites : dict
-        From :func:`_parse_composites`
-
-    """
-    _sanity_check(fh)
-    header = _parse_header(fh)
-    cmetrics_by_ascii, cmetrics_by_name = _parse_char_metrics(fh)
-    kernpairs, composites = _parse_optional(fh)
-    return header, cmetrics_by_ascii, cmetrics_by_name, kernpairs, composites
-
-
 class AFM:
 
     def __init__(self, fh):
         """Parse the AFM file in file object *fh*."""
-        (self._header,
-         self._metrics,
-         self._metrics_by_name,
-         self._kern,
-         self._composite) = _parse_afm(fh)
+        self._header = _parse_header(fh)
+        self._metrics, self._metrics_by_name = _parse_char_metrics(fh)
+        self._kern, self._composite = _parse_optional(fh)
 
     def get_bbox_char(self, c, isord=False):
         if not isord:
